Hydraulic cushioning unit with boot type accumulator

ABSTRACT

A hydraulic cushioning unit for railway cars includes a cylinder with a piston and piston rod assembly reciprocable therein and which during cushioning operation provides for the flow of fluid between chambers and through an orifice and through the piston rod to a low pressure reservoir. The reservoir or accumulator is a flexible boot type having one end connected to the cylinder and the other end secured to the piston rod. Fluid is directed from the piston rod through a deflector against an inner cylindrical surface of the boot type reservoir. The reservoir is shaped to provide for an optimum in efficiency and wearability.

United States Patent [191 2 Anderson et al.

[54] HYDRAULIC CUSHIONING UNIT WITH BOOT TYPE ACCUMULATOR [75] Inventors: Steven A. Anderson, Elwood, 111.; Eugene C. Barker; Tung Han Yang, both of Munster, Ind.

[73] Assignee: Pullman Incorporated, Chicago, Ill.

[22] Filed: Mar. 26, 1971 [21] Appl. No.: 128,289

[52] U.S. C1 ..2l3/43, 188/317, 267/65 R [51] Int. Cl. ..B6lg 9/08, B6lg 9/16 [58] Field of Search .213/8, 43, 222; 267/64 R, 65 R;

55 References Cited UNITED STATES PATENTS 3,150,783 9/1964 Campbell et al. ..213/43 [111 3,724,61 [451 Apr. 3, 1973 7/1968 Rasmussen ..2l3/43 7/1969 Thompson ..2l3/43 [57] ABSTRACT A hydraulic cushioning unit for railway cars includes a cylinder with a piston and piston rod assembly reciprocable therein and which during cushioning operation provides for the flow of fluid between chambers and through an orifice'and through the piston rod to a low pressure reservoir. The reservoir or accumulator is a flexible boot type having one end connected to the cylinder and the other end secured to the piston rod. Fluid is directed from the piston rod through a deflector against an inner cylindrical surface of the boot .type reservoir. The reservoir is shaped to provide for an optimum in efficiency and wearability.-

5 Claims, 4 Drawing Figures PATENTEDAPR 3 I973 SHEET 1 BF 2 INVENTORS STEVEN A. ANDERSON EM T Rm A

iii

PATENTEUAPR 3 I975 SHEET 2 0F 2 INVENTORS TUNG HAN YANG STEVEN A. ANDERSON EUGENE C. BARKER f/l/Illll HYDRAULIC CUSHIONING UNIT WITI-I BOOT TYPE ACCUMULATOR CROSS REFERENCE TO RELATED APPLICATIONS Spence et al. Ser. No. 1 16,047 filed Feb. 17,1971,

now US. Pat. No. 3,679,069. Shaver et al. Ser. No. 116,048 filed Feb. 17,1971

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns hydraulic cushioning units of a type utilized in railway car application and which include flexible boot-like accumulators or reservoirs for storing the fluid flow from chambers in the cylinder to a low pressure chamber during the cushioning action of the unit.

2. Description of the Prior Art Hydraulic cushioning devices for railway cars which include boot type flexible accumulators or reservoirs as shown in' Rasmussen, US. Pat. No. 3,330,422 patented July 1 l, 1967 and 3,392,849 patented July 16, 1968.

' SUMMARY In the constructions shown in the aforementioned patents and related patent application, flexible boot type reservoirs or accumulators are utilized which receive fluid from high pressure chambers during movement of a cylinder and piston rod assembly from an extended to a retracted position as a result of buff and draft impacts on the car couplers. In these constructions the piston rod is of a hollow type through which fluid flow escapes by means of orifices in turn filling the flexible boot which is connected at one end to the piston rod and at its other end to a portion of the cylinder, the same providing an accumulator and also serving to seal the unit. In the aforementioned application, Spence et al., Ser. No. 1 16,647 a deflector is provided immediately radially outwardly of the discharge orifices in the piston rod to deflect the fluid in a manner preventing erosion and damage to the interior of the boot. It is therefore a prime object of the invention to provide a boot of a construction and configuration accommodating such deflector so as to provide rolling movement of the boot when the piston rod is moved to its retracted position and to assure optimum performance and long maintenance-free life of the boot.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view through an improved hydraulic cushioning unit;

FIG. 2 is an enlarged side elevational view of a portion of the cushioning unit showing particularly a flexible boot or reservoir;

FIG. 3 is an enlarged cross-sectional view through a portion of a cushioning unit boot assembly and deflector arrangement; and

FIG. 4 is a detailed cross-sectional view through an improved hydraulic boot or accumulator per se.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a hydraulic cushioning unit comprises a cylinder 11 having an inner cylindrical wall surface 12 and an outer cylindrical wall surface 13. One end of the cylinder 11 is closed by means of a cylinder head 14 and the other end of the cylinder 11 is open as indicated at 15. Conventional car couplers are connected to the heads 14, and such cushioning units are disposed at opposite ends of the car, the couplers projecting outwardly from the center sill. A return spring 16 is suitably positioned around the outer cylindrical wall surface 13 and is retained at one end by means of a retainer stop 17 and a slidable ring 18. The other end of the spring is in engagement with a retainer stop 19 on the cylinder 11. The cushioning unit 10 is of a metered type to provide a substantially constant force travel during the operation thereof resulting from draft and bufi impacts. To provide for such constant force action a metering pin 21 includes suitable metering flutes 22 and is rigidly connected to the head 14 projecting longitudinally therefrom within the cylinder 11. A piston 23 is positioned for reciprocation within the cylinder 1 1. The piston 23 is provided on one side with a pocket 24 having a metering valve plate 25 movably disposed therein. The valve plate 25 also includes a metering orifice 26 which cooperates with the metering pin 21 to provide for metered flow of fluid from the high pressure buff chamber A on one side of the piston 23 to a high pressure draft chamber B which is disposed on the other side of the piston 23. A threaded end portion 27 of a piston rod 28 is securely connected to the piston 23. The piston rod 28 includes an elongated passageway or bore 29 which receives fluid from the chamber A through the orifice 26 and discharges the. same through a plurality of radial ports or orifices 30 provided in the piston rod 28 as best shown in FIG. 3. A plurality of converging bores 31 are also provided in the piston rod 28 and communicate with the passageway 29 and chamber B for providing additional means for metered fluid flow during a draft impact. The piston rod 28 also is provided at its end with an end plate 32.

A cylinder head 33 is positioned between the open end 15 and the head 14 within the cylinder 11. The cylinder head 33 is provided with a longitudinal bore 34 communicating with a cavity 35. An apertured retainer plate 36 is retained at one end of the cavity 35 by means of a snap ring 37. A movable valve element 38 is adapted to be moved over the bore 34 in one position to close the same.

A cylindrical boot protector 3 9 is suitably connected within the cylinder 11 to the intermediate cylinder head 33. The protector 39 is more specifically described in the aforementioned related patent application, Shaver et al., Ser. No. 116,048, now US. Pat. No. 3,679,069.

A deflector 40 as best shown in FIGS. 1 and 3 is fixedly connected to the piston rod 28 and is provided at one end with an annular shoulder 41 which supports the same about the peripheral surface of the piston rod 28. The deflector 40 includes a cylindrical wall 42 provided with ports 41' and at one end with an end flange portion defining an opening 43 extending longitudinally outwardly of the deflector. The annular shoulder 41 is also provided with a circumferentially extending undercut seat 44. The end flange includes spacer members 44' supported on the piston rod 28. An accumulator boot or reservoir 45 of flexible material includes an elongated longitudinally extending cylindrical wall 46. The wall 46 comprises a first cylindrical section 47 of a certain substantially constant inner and outer diameter. A second cylindrical section 48 of an outer and inner diameter less than the diameter of the first cylindrical section 47 is disposed at the other end of the wall 46. A frusto-conical transition section 49 also of substantially constant inner and outer diameter is connected to the first and second sections 47 and 48, respectively. The accumulator 45 is provided with a frusto-conical end section 51 having connected thereto a metal ring reinforced attaching flange 52. As shown in FIG. 4 the other end of the accumulator boot or reservoir 45 is provided with a frusto-conical end section 53 having a ring reinforced attaching flange 54. As shown in FIG. 1, the flange 52 is adapted to be securely clamped to the cylinder head 33 by means of an attaching ring 55 as further described in the aforementioned applications.

In the assembled condition of the boot accumulator 45 the end section 53 is reversely bent as indicated at 56 and as shown in FIG. 3 the attaching flange 54 is securely clamped within the annular seat 44 by means of a ring 57 held in position by a sleeve 58 which in turn is suitably connected to the piston rod 28.

In the aforementioned U.S. Pat. No. 3,330,422 the construction of a flexible boot type accumulator is disclosed and the present boot 45 may be similarly constructed including an inner rubber cylindrical liner 59 having first cords 60 suitably embedded in a rubber sheet and second cords 61 also suitably embedded in a rubber sheet molded with the inner rubber liner 59 in an outer rubber liner 62 to provide an integral molded construction.

THE OPERATION In the operation a hydraulic cushioning unit is disposed in a suitable manner within each of the opposite ends of the fixed center sill of a railway car. A suitable coupler is connected through a yoke arrangement (not shown) to the cylinder head 14 and the plate 32 is suitably secured rigidly within the center sill. FIG. 1 shows the neutral or extended position of the piston 23 and piston rod assembly 28. Upon an impact the cylinder 11 is moved to the left causing movement of the piston 23 to the right forcing fluid from the chamber A through the metering orifice 26, to the passageway 29, and outwardly through the bores 30 and 31. Fluid flowing through the ports 30 and outwardly through ports 42' and opening 43 flow into the accumulator or reservoir 45. The ports 31 function as metering means when a draft impact results during train action. Movement of the cylinder in draft will result in fluid flow from the chamber B through ports 31 through passageway 29. The function of the deflector 40 is well explained in the aforementioned patent application Spence et al., Ser. No. 116,047, now U.S. Pat. No. 3,679,069.

The boot shape with which the present invention is concerned is of primary importance in that the section 47 is disposed in radially spaced relation outwardly of the piston rod 28 and the cylindrical wall 42 of the deflector 40. The radial spacing of the section 47 is substantially constant with respect to the outer diameter of the piston rod 28 to provide an annular space extending from one end of the accumulator to the area of the orifices 30. Thus during the initial movement of the piston rod 28, the boot 45 is maintained in spaced relation with respect to the deflector 40. Therefore, movement will not cause interference between the boot and deflector which otherwise could cause compressive forces being placed upon the wall sections 48, 49 and 51 and which might have a tendency to buckle the section 51 adjacent its point of connection by means of the retaining ring 55. In other words, the normal compressive forces resulting from the movement of the piston rod to the right in FIG. 1 are not increased over normal forces since the annular space provided between the deflector 40 and the inner surface of the section 47 does not result in any binding against said deflector. Thus, boot wear at this particular portion is completely avoided and maximum efficiency and long life will result. Further, the transition wall section 49 is a frustoconical shape but the angle is very small, preferably being in the area of around 5 so that there is no opportunity of the deflector 40 becoming wedged against the inner circumferential surface of the transition wall during movement of the piston rod to its retracted position. Again, wear is eliminated at this particular section while the strength of the section 48 is maintained, the same resulting from a relatively smaller inner and outer diameter in relation to the section 47. By maintaining the section 48 also of a lesser diameter than the section 47, there is less of a possibility of the outer circumferential surface of the section 48 wearing against the inner wall 12 of the cylinder 11. Thus, this latter possibility is also excluded by virtue of the improved shape of the boot reservoir.

Thus, it is apparent that the larger diameter section 47 prevents the boot from contacting the deflector 40 which sets up undesirable stresses on the remaining sections of the boot. Further, the smaller diameter of section 48 prevents the possibility of the section coming into contact with the inner surface 12 of the cylinder 11 which otherwise might cause bulging of the section causing premature wear. Also, the transition section 48 having a gradual tapering inner wall precludes the possibility of the deflector 40 engaging the said wall causing further bulging of the boot sections. Further, the relatively narrower inner and outer diameter of the section 48 and the frusto-conical end section 51 provide for additional strength and prevent contact of the section with the inner surface 12 of the cylinder 11.

We claim:

1. In a hydraulic cushioning device including:

a hydraulic cylinder having a first cylinder head closing one end thereof,

a second cylinder head disposed in said cylinder longitudinally spaced from said first cylinder head, said second head including an axially extending bore,

a piston rod slidable through said bore from an extended to a retracted position relative to said cylinder,

said rod including a piston slidable between said cylinder heads and providing'on one side of said piston and said first head a chamber,

a longitudinal passageway within said rod communicating with said chamber,

a flexible boot type accumulator,

means connecting one end of said accumulator to said piston rod,

an orifice in said rod positioned substantially adjacent said means connecting one end of said accumulator to said piston rod,

deflecting means connected to said piston rod adapted to overlie said orifice,

means connecting a second end of said accumulator to said hydraulic cylinder whereby said accumulator and chamber are sealed from the atmosphere and during movement of said piston rod to a retracted position fluid may be directed through said passageway orifice and deflector to said accumulator, the improvement comprising:

said accumulator including an elongated cylindrical wall extending longitudinally and around said piston rod, and

said cylindrical wall in said extended position of said rod having a first cylindrical wall section of substantially constant diameter radially spaced outwardly of said rod and extending from said first end of said accumulator to said orifice to provide an annular space extending from said first end at least into the area of said orifice and said deflecting means being positioned in said annular space.

2. The invention in accordance with claim 1,

a second cylindrical wall section longitudinally spaced from said first wall section,

said second wall section having a substantially constant diameter less than said first wall section, and

a transition wall section of frusto-conical shape connecting said first and second sections, said transition wall section being disposed angularly with respect to said first and second wall sections to conform to their relative differences in diameter.

3. The invention in accordance with claim 2,

said second wall section at one end thereof adjacent the second connecting end of said accumulator being of frusto-conical shape and increasing in diameter toward the end thereof.

4. The invention in accordance with claim 2,

said first wall section having at the first connecting end of said accumulator an end portion reversely turned in underlapping relation relative to a portion of said first wall section and substantially conforming to the diameter of said piston rod.

5. The invention in accordance with claim 1,

said deflecting means including a cylindrical deflector wall in said annular space, the outer peripheral surface of said cylindrical deflector wall and the inner peripheral surface of said cylindrical deflector wall being respectively radially spaced 'from said first cylindrical wall section and said piston rod.

' s s =0: s 

1. In a hydraulic cushioning device including: a hydraulic cylinder having a first cylinder head closing one end thereof, a second cylinder head disposed in said cylinder longitudinally spaced from said first cylinder head, said second head including an axially extending bore, a piston rod slidable through said bore from an extended to a retracted position relative to said cylinder, said rod including a piston slidable between said cylinder heads and providing on one side of said piston and said first head a chamber, a longitudinal passageway within said rod communicating with said chamber, a flexible boot type accumulator, means connecting one end of said accumulator to said piston rod, an orifice in said rod positioned substantially adjacent said means connecting one end of said accumulator to said piston rod, deflecting means connected to said piston rod adapted to overlie said orifice, means connecting a second end of said accumulator to said hydraulic cylinder whereby said accumulator and chamber are sealed from the atmosphere and during movement of said piston rod to a retracted position fluid may be directed through said passageway orifice and deflector to said accumulator, the improvement comprising: said accumulator including an elongated cylindrical wall extending longitudinally and around said piston rod, and said cylindrical wall in said extended position of said rod having a first cylindrical wall section of substantially constant diameter radially spaced outwardly of said rod and extending from said first end of said accumulator to said orifice to provide an annular space extending from said first end at least into the area of said orifice and said deflecting means being positioned in said annular space.
 2. The invention in accordance with claim 1, a second cylindrical wall section longitudinally spaced from said first wall section, said second wall section having a substantially constant diameter less than said first wall section, and a transition wall section of frusto-conical shape connecting said first and second sections, said transition wall section being disposed angularly with respect to said first and second wall sections to conform to their relative differences in diameter.
 3. The invention in accordance with claim 2, said second wall section at one end thereof adjacent the second connecting end of said accumulator being of frusto-conical shape and increasing in diameter toward the end thereof.
 4. The invention in accordance with claim 2, said first wall seCtion having at the first connecting end of said accumulator an end portion reversely turned in underlapping relation relative to a portion of said first wall section and substantially conforming to the diameter of said piston rod.
 5. The invention in accordance with claim 1, said deflecting means including a cylindrical deflector wall in said annular space, the outer peripheral surface of said cylindrical deflector wall and the inner peripheral surface of said cylindrical deflector wall being respectively radially spaced from said first cylindrical wall section and said piston rod. 